Treatment needs based on the existence of clinical conditions are important determinants along with socioeconomic variables of the demand for dental services and dental manpower. Little information is currently available on the extent of needs in the U.S. This study will result in a series of reports. One report will describe the types and the amount of treatment needed by the U.S. population in 1981. From a household probability survey of 7700 persons in the U.S., information was collected on the condition (sound, filled, missing, etc.) and the needed treatment (filling, crown, extraction, etc.) of each permanent tooth. Information was also collected on type of prosthesis (full, partial, fixed) present and needed for each permanent tooth. Selected findings follow: 43 percent of the U.S. population needed 1 or more restorations at the time of examination; 37 percent needed a posterior restoration while only 18 percent needed an anterior restoration; 9 percent needed an extraction; 2 percent needed endodontics; 4 percent needed an anterior crown; and 11 percent needed a posterior crown. The total cost in 1985 dollars to treat these conditions is estimated at slightly over 100 billion dollars. Close to 70 percent of the total is for the placement of a new prosthesis where none existed at the time of exam. Persons 55 years and older accounted for 30 percent of the cost while persons 35 to 54 accounted for 40 percent.